Then there’s another type of operation to check fares that happens semi-regularly and is much more intense. There, dozens of officers take over a station for hours, checking every single rider’s proof of fare and pulling aside each person who doesn’t have one.

Some residents in the area where these efforts overwhelmingly take place inevitably see these operations — and MTS personnel in general — as a security force they constantly have to deal with, even when they’re not doing anything wrong.

MTS let me tag along for one operation. It’s a show of force, often with eight to 10 security personnel for every one resident waiting for a trolley. Apprehensive-looking riders tip-toe off of trolley cars at the sight of a platform teeming with officers.

Originally, MTS told me it chooses the locations for those intense operations at random.

“Literally from a hat,” MTS spokesman Rob Schupp wrote in an email.

They’re not random. And MTS has since admitted as much.

“Turns out swarms aren’t as random as I thought,” he wrote in a follow-up email, along with data showing the locations of the operations. “They concentrate on the downtown area where all of our lines intersect and we have the most fare evasion.”

Indeed, the numbers show the areas where fare evasion was lowest were home to the fewest operations.

Unlike the Sheriff’s Department sweeps, MTS’s efforts really do seek to crack down on fare evasion. They’re not trying to arrest people who they suspect might be likely to commit major crimes in the future, though people are asked about outstanding warrants or whether they’re on probation or parole if they’re found without a fare. For the Sheriff’s Department, fare evasion is mostly just a pretext to question people and identify other possible offenses.

MTS security runs two types of more aggressive fare enforcement, on top of the routine daily fare checks.

One is called a swarm, where a few officers in plain clothes board a train and start asking for proof of fare. The other, “Special Enforcement Units” or SEUs, are when dozens of officers take over a station for an extended period.

The undercover swarms happened overwhelmingly at the Imperial and 12th Avenue station, where all three trolley lines intersect and ridership is the highest, or on the trolley leg downtown between City College and Santa Fe Depot. Of the 24 swarms in the first six months of 2014, 21 were in those two locations.

Data from the special enforcement units provided by MTS shows they too were concentrated downtown, but also in areas along the southeastern portion of the trolley system.

Of the 26 operations in 2014, six were held in Lemon Grove, the most of any station.

But on a wide swath of the Green Line, from Old Town to SDSU through Mission Valley, the 11 stations there had just two operations, both at the Fashion Valley Transit Center. (And, to Schupp’s point, the rate of fare evasion found during those two stops was the lowest during the course of the year.)

“We have capability to check on parole violations or warrants, but fare enforcement is our duty,” said Elisio Alilin, a supervisor for MTS’s code compliance department who oversaw an SEU at the downtown La Mesa station on Oct. 29.

The public show of authority is a striking sight, though, when a trolley pulls into a station and 30 security officers jump into action. Or when someone without a fare is led to a special area for further questioning, surrounded by a handful of MTS security.

For 54-year-old Daniel Rivero, who received a $198 fare evasion citation at an enforcement sting at the La Mesa station in October, it was a remarkable sight.

“I’ve seen them do the undercover stuff where they board the train, but I’ve never seen them do this gestapo shit,” he said.

During the same operation, 18-year-old Forest Sessions was let off with a warning: He told officers the ticket machine where he boarded was busted, and a call over to that station confirmed his story. Still, he wasn’t pleased about being pulled off the trolley and delayed for 30 minutes during the ordeal.

“I’ve never seen all this police shit,” he said. “I mean, just look at this. Look how many people it takes to write a ticket.”

Alilin said he encourages security personnel to exercise discretion. He understands things can happen and tries to be compassionate.

“We want to hear everyone’s story,” he said. “If someone honestly couldn’t work the machine, and the train came so they jumped on, we’ll let them buy their fare at the next stop and help them out.”

Through the year, 86,979 trolley riders came through an MTS fare enforcement sting. Of those, 2,958 received a citation of any kind.

The overwhelming majority of those citations were for fare evasion, meaning MTS found a roughly 3.5 percent evasion rate, which is in line with expectations for a “proof of payment”-based fare system.

Levondren Price, a 21-year-old Encanto resident who lives near one stop and works at another, got a $198 fare violation ticket during a sheriff-led operation. He said he sees MTS security officers questioning young people at the Euclid Avenue station near the Food 4 Less where he works.

“When I get off work and I have my uniform on, they don’t really say anything to me,” he said. “But when I’m not at work, I just go straight home because I don’t want to deal with them any more than I have to. Every time I get on the trolley, I’m looking out for them because even if I still have my pass I could still get questioned.”

Edwaun Thames, who works at the Imperial Barbershop in Encanto, said a couple years ago he got a loitering citation at the City College station for being there without a ticket; that station occupies the ground floor of the Smart Corner building, where he lived at the time.